DESCRIPTION: This application will study two hypotheses: 1) the ability of intestinal epithelial cells to respond to an inflammatory stimulus is dependent on the state of cell differentiation and 2) nutrients including butyrate and vitamin D are capable of inducing differentiation and as such can inhibit expression by epithelial cells of the intestine of inflammatory mediators. There are three Specific Aims: 1) to determine the mechanism of differentiation by butyrate and vitamin D concomitant with inhibition of IL-8 expression. The role of histone hyperacetylation will be explored for butyrate mediated differentiation and the role of intracellular calcium and vitamin D receptor studied for vitamin D induced differentiation. The next Specific Aim examines IL-8 gene expression with regard to transcriptional repression and MRNA stability, definition of promotor sequences of the IL-8 gene which inhibit transcription as well as mapping of Dnase 1 hypersensitive sites. Finally, to ascertain cis-acting elements by Dnase 1 footprinting, electrophoretic mobility shift assay and site directed mutagenesis in chimeric and minigene constructs of the IL-8 gene.